Terbium complexes encapsulated in hierarchically organized hybrid MOF particles toward stable luminescence in aqueous media

To exert the respective advantages of lanthanide complexes and metal–organic frameworks (MOFs) in luminescence and encapsulation, hierarchically organized hybrid MOF particles were developed to meet the requirements of stable luminescence for applications in biological media. Anionic terbium (Tb) complexes sensitized by tridentate pyridine-tetrazolate (pytz) ligands (i.e. Tb(pytz)3) were encapsulated in zeolitic imidazolate framework-8 (ZIF-8) nanoparticles (~150 nm). TIF-1Zn (Zn(DMBIM)2) frameworks were then hybridized with ZIF-8 by the mediation of a hydrophobic ligand, i.e. DMBIM (5,6-dimethylbenzimidazole). A bio-inspired polymer, i.e. polydopamine, was utilized for imparting the particles with hydrophilicity and functionalization ability. An unprecedentedly high quantum yield (82.0%) and luminescence stability in PBS buffer was realized by the hierarchical structure.